Sunless tanning, also called self-tanning, is the ability to impart a tan to fair or light skin without the use of sunlight. In order to achieve a tanned look or otherwise darken their skin, individuals can expose their skin to sunlight or a source of simulated sunlight, e.g., a solar simulator or ultraviolet lamps. For many individuals, such exposure will stimulate formation of new melanin pigment and retention or increased amount of melanin in the epidermis and produce a darkened skin color. However, some individuals find that such exposure does not produce the desired melanin formation and as a result the desired tan is not obtained. Additionally, exposure to the sun or a source of ultraviolet radiation can have deleterious effects for many individuals and can, in fact, cause sunburn, skin blistering, premature skin aging or skin cancer. Self-tanning or sunless tanning compositions offer a safe alternative and enable these individuals to obtain the desired tanned look.
Commercial formulations, using dihydroxyacetone [DHA], applied locally to the skin, were developed for this purpose. Subsequent formulations using amino acids or amino functional materials when applied sequentially or simultaneously with incorporated DHA produced a faster, more natural and longer lasting artificial effect.
In experimenting with various compositions for improving sunless tanning formulations, applicant accidentally added methylsulfonyl methane, also known as methyl sulfone, [MSM], instead of the addition of amino acids, and found much to his surprise that the product was a substantially improved formulation.
MSM is claimed to have nutritional properties when taken orally. It is currently popular as a nutritional supplement; When applied topically it can assist in softening skin and nails. However applicant has not found any references suggesting the use of MSM in self-tanning or sun care compositions or suggesting that MSM could enhance penetration of the skin by any topical application thereto.
Applicant used his MSM formulation as a pre-tan accelerator and then applied a conventional self tanner composition not containing MSM. Applicant then used a conventional accelerator and applied the same conventional self tanner composition. Use of applicant""s accelerator in this manner produced a darker and more intense tan then use of accelerators containing amino acids but without MSM. More particularly, skin sites treated with MSM or MSM plus amino acids in the pre-tan accelerator plus the self tanner had a longer lasting and darker tan than the skin sites treated with no MSM or with an amino acid containing pre-tan accelerator and a self tanner.
Applicant also incorporated MSM in self tanner formulations containing DHA and used it in comparison with formulations that contained no MSM. The tan produced by applicant""s formulation remained darker and lasted several days longer then the conventional self-tanning formulation.
Applicant has conducted experiments with a typical oil-in-water self tanning cream containing DHA as the self tanning agent with or without the inclusion of MSM. The self tanning composition using MSM produced a tan that developed at a more rapid rate, was more intense, and lasted longer than the same composition without MSM. Applicant also conducted experiments with DHA containing self-tanning liquid mousse compositions, with and without MSM. Again, the self-tanning composition with MSM produced a tan that developed at a more rapid rate, was more intense, and lasted longer than the same composition without MSM.
Consequently, in accordance with the principles of this invention, MSM enhances the performance of DHA containing self-tanning compositions when used sequentially, simultaneously, or subsequently in conjunction with self-tanners. MSM does not react chemically with DHA but it acts as if it is a skin penetrant to facilitate DHA penetration.
Additions of 5% MSM to DHA formulas, either with or without soluble dyes, enhances tanning effect producing a more intense hue that lasts longer. The use of MSM as an accelerator also produces a more intense hue. The best results were produced with an addition of 5% MSM. Similar but less pronounced effects were obtained with additions as low as 1% and as high as 20%. A 0.1% addition of MSM was ineffective. The solubility of MSM in water is limited to about a 20% addition so additions above this range were not attempted.